1. Field of the Invention
The present invention relates to towing accessories and, more particularly without limitation, to tow bars for connecting a towing vehicle to a towed vehicle.
2. Description of the Related Art
A tow bar is typically used for connecting a towing hitch arrangement of a towing vehicle to a towed hitch arrangement of a vehicle to be towed, sometimes referred to herein as a towed vehicle. For most applications, the tow bar, which connects the front end of the towed vehicle to the rear end of the towing vehicle, has two tow bar legs wherein each tow bar leg has one end spaced in close proximity to the corresponding end of the other tow bar leg to form an apex, and the other ends of the tow bar legs are spaced apart forming the sides of an isosceles triangle. The triangular configuration causes the towed vehicle to closely track the towing vehicle, both along straightaways and around corners.
For tow bar applications, such as where heavy massive equipment is moved a relatively short distance, such as where an airliner is backed away from a terminal for example, the tow bar may have only one tow bar leg. For such applications, one end of the tow bar leg may be connected to the front end of the towed vehicle and the other end of the tow bar leg connected to the front end of the towing vehicle so the operator of the towing vehicle can face the towed vehicle to thereby enable a user to carefully observe the response of the towed vehicle as it is being slowly displaced by the towing vehicle.
Tow bars are generally structured to accommodate variations in attitude that inherently exist between the towing and towed vehicles, which variations are constantly occurring and continuously changing. One such variation in attitude between the vehicles is the instantaneous sidewise tilt of the towing vehicle relative to the instantaneous sidewise tilt of the towed vehicle, such as the rocking motion which occurs when traversing uneven or rough underlying surfaces for example. This phenomenon, sometimes referred to as “roll”, can be accommodated by tow bar apparatus designed to accommodate rotations between the towing and towed vehicles about a longitudinal, horizontal axis, see the “x”-axis in FIG. 1.
Another such variation in attitude between the vehicles is the instantaneous horizontal direction in which the towing vehicle is traveling relative to the instantaneous horizontal direction in which the towed vehicle is traveling, such as when the vehicles are traversing an unbanked corner for example. This phenomenon, sometimes referred to as “yaw”, can be accommodated by apparatus designed to accommodate rotations between the towing and towed vehicles about a vertical axis, see the “y”-axis in FIG. 1.
Finally, another such variation in attitude between the vehicles is the instantaneous elevation of the towing vehicle relative to the instantaneous elevation of the towed vehicle. A related variation in attitude between the vehicles is the instantaneous ascent/descent orientation of the towing vehicle relative to the instantaneous ascent/descent orientation of the towed vehicle. Both of these related variations in attitude can be accommodated by apparatus designed to accommodate rotations between the towing and towed vehicles about a transverse, horizontal axis, sometimes referred to as the “pitch” axis, see the “z”-axis in FIG. 1.
During actual towing procedures, all combinations of the roll, yaw and pitch phenomena are constantly occurring and continuously changing. Prior art is replete with tow bar designs that have been developed in an attempt to accommodate these phenomena, some of those designs being more successful than others. For example, a ball hitch/hitch ball receiver combination securing a tow bar to a towing vehicle can theoretically accommodate all three of the roll, yaw and pitch phenomena. Although the ability of such a combination to accommodate yaw is encouraging, unfortunately the ability of such a combination to accommodate either pitch or roll is extremely limited, where failure to closely abide by such limitations can produce disastrous and even fatal results.
Another commonly used arrangement involves using a conventional receiver hitch in combination with a square tube-shaped shank. Although such an arrangement may be convenient for connecting a tow bar to a towing vehicle, this type of connection by itself provides absolutely no ability to accommodate any one of the three roll, yaw or pitch phenomena. As a result, the tow bar and/or the connections between the tow bar and the vehicles must be relied upon to provide a solution for minimizing the potentially detrimental effects of this type of hitch arrangement.
Still another commonly used arrangement involves using a pintle hitch in combination with a lunette ring, particularly for towing heavy military or construction equipment. Although this combination has the ability to accommodate pitch and yaw, unfortunately the ability of this combination to accommodate roll is somewhat limited. Also, due to a typical looseness of fit between the pintle hitch and the lunette ring, some swaying of the towed vehicle relative to the towing vehicle inherently occurs.
The ability to manually utilize all three pitch, yaw and roll rotations generally greatly simplifies connecting a tow bar between the towing and towed vehicles. For example, a tow bar is sometimes first connected to a towing vehicle followed by connecting the tow bar to the towed vehicle. Some tow bars require precise fore-to-aft, horizontal, and/or angular alignment of the two tow bar leg connectors with mating connectors of the towed hitch arrangement so connecting pins can be inserted through aligned orifices while the tow bar components are being manually held in place.
Such activity can be extremely stressful, sometimes requiring the efforts of more than one person, particularly when connecting massive tow bars such as those used for towing heavy military or construction equipment for example. Such stress and effort could be substantially reduced if each of the tow bar leg connectors could be individually articulated in close proximity to the towed vehicle so each tow bar leg connector can be easily and conveniently mated with the hitch arrangement of the towed vehicle.
What is preferred is a tow bar wherein each tow bar leg can be easily and independently articulated, both three-dimensionally and about all three axes, to thereby simplify and expedite connecting a tow bar between the vehicles.
Although some prior art tow bars have self-storing capability so they can remain attached to the rear end of a towing vehicle or to the front end of a towed vehicle, many of such prior art tow bars have parts which are difficult to apply, unreliable, and/or easily lost or misplaced, and/or require the use of installation tools which may also be easily lost, misplaced or unavailable when needed.
What is needed is a tow bar having self-storing capability which is structured to provide ease and reliability of storage and eliminates the possibility of loss or misplacement of components thereof and also eliminates the need for tools—which may also be lost, misplaced or unavailable when needed—for installing such components.
Some prior art tow bars have tubularly-shaped legs, which are commonly used not only for their esthetic appearance but also for their ease of handling and for their strength characteristics. For example, strength characteristics of tubular legs can generally be improved by simply providing tubes with thicker walls.
An example of a prior art tow bar which provides some of the above-mentioned features is disclosed in U.S. Pat. No. 8,353,522 to Helland et al. for a “Towing Assembly”. Unfortunately, Helland et al. requires extra bolts and nuts for locking the angular orientation of the tow bar legs relative to a lunette ring, and requires even further extra bolts and nuts for locking the different shafts of the tow bar legs in end-to-end configurations. As aforesaid, it is not uncommon for such bolts and nuts to be lost or misplaced prior to and during installation thereby complicating and frustrating connections between the towing and towed vehicles, not to mention the loss, misplacement or unavailability of tools needed to install those extra bolts and nuts.
What is needed is a locking mechanism structured as a non-removable element of the tow bar, wherein separate extra parts and the need for tools to install those separate extra parts, are eliminated.
In addition, the pivot joints of the tow bar legs, as in the of Helland-type apparatus for example, may be the weakest features of the tow bar due to the largely unprotected exposure of such joints to debris and other environmental hazards, and have reduced capability to withstand the substantial stresses and strains to which tow bars are subjected.
What is needed is a mechanism structured to not only shield and protect pivot features of the joints but also to reinforce and further strengthen the tow bar legs themselves.
Another tow bar leg feature that can sometimes simplify facilitating on-vehicle storage is to provide articulated legs. As aforesaid, the pivot joints that provide the articulation is generally the weakest part of such tow bar legs, which jeopardizes the ability of such tow bars to withstand the harsh adverse environment to which tow bars are subjected.
What is needed is a tow bar having legs which exhibit desirable aligned tubular characteristics for towing purposes, and which are easily and quickly convertible to an articulated structure for on-vehicle storage purposes, wherein the tow bar is simply and easily convertible from and to a stored configuration and a deployed configuration without the need for installing or removing extra parts and/or the need for tools to install or remove those extra parts.